Bitcoin mining hardware producer CoinTerra has moved to reassure customers after it emerged a number of complaints about the company have been lodged with the Better Business Bureau (BBB).

Some 11 complaints relating to CoinTerra have been closed with the BBB in the last 12 months. Two of these related to advertising and sales issues, one related to guarantee and warranty issues and eight related to problems with the company's products or service.

The BBB is a private entity, not a government agency, which aims to improve trust between consumers and businesses.

Complaints are closed when some form of resolution is reached between the customer and company. The BBB only details the number of closed complaints, so it is not known how many active complaints about CoinTerra the organisation is currently dealing with.

The main complaints being voiced on bitcoin forums, including Bitcoin Talk and reddit, by CoinTerra customers relate to delays in the processing of refunds.

CoinTerra is offering refunds to the January and February batch of retail customers who paid for the first production of its TerraMiner IV units.

This mining hardware unit promised to deliver 2TH/s using 1,650W of power, but the company's testing revealed it was only running between 1.63TH/s and 1.72TH/s, with power draw between 1,900W and 2,100W.

Customers were offered the following two options:

1. For January or February batch retail customers who wish to receive their TerraMiner order in the currently-shipping specification we will offer a 15% discount coupon* redeemable against their next retail hardware order placed at the CoinTerra website store. If a January or February batch retail customer chooses to accept their order as-is they will automatically receive this coupon.

2. We understand that some January or February batch customers may wish to request a refund, in which case we will offer a full refund of US dollars received for their order. Customers wishing to request a refund should contact support@cointerra.com with their unique order ID. For those customers who choose the refund option we would like to extend the offer of a 5% discount coupon* redeemable against their next retail hardware order placed at the CoinTerra website store.

The company's statement didn't provide any information on how long the refund process would take, but there have been many complaints from customers that they have been waiting months for their money.

One customer told CoinDesk he had opted for a refund and was told by CoinTerra it would take three or four weeks to be processed.

"They first stated I had to wait 3-4 weeks for processing. I waited, the four-week mark passed and nothing. I'm over the 10-week mark now," he said.

Daniel Larsson, press officer at CoinTerra, said the company's goal has always been to process legitimate refund requests as quickly as possible, adding:

He explained that CoinTerra processes refunds via cheque for those living in the US and via wire transfer for international customers.

A significant number of the company's customers pay for their miners in bitcoins through a transaction processor, which then converts the bitcoins into US dollars.

Larsson said CoinTerra ultimately receives dollars and refunds in dollars, which means it has to perform identity verification.

"Partly as a result of this time-consuming process, we are currently experiencing a short-term backlog that we are working to clear as quickly as practically possible," he said.

Larsson confirmed that over half of the total refund requests have been processed, with the remaining refund queue comprising around 200 orders.

"Our goal is to have all remaining refund requests processed by the end of the month," he said.

Customers have also been complaining that there has been a lack of communication from the company, with one stating: "There is no way to get in touch with them. They won't answer their phones, the won't answer any emails."

Larsson said the company recognises that, due to a large volume of customer support requests, its response time to some customers has been less than ideal.

CoinTerra's goal is to respond to customer inquiries within 24 hours, but this has been difficult to achieve recently, he added.

CoinTerra's most recent statement announced the launch of CoinTerra Mining, the company's new cloud-based mining contracts product.

A number of customers who had previously requested refunds have now decided to switch their refund request to a CoinTerra Mining contract instead.

Larsson suggested the company currently has some new projects under development, but refused to elaborate any further.

It has been reported, though, that CoinTerra plans to build its own data centre in order to facilitate its new cloud-mining offering.