Awful customer service

If I could have given no stars I would. So quick to demand payment, and when I ask for banking details I get such a quick response within 1 day. I then make payment, send proof of payment and ask for a paid up letter and 6 days later no response, just an account running further into arrears. I have been trying to contact them for 6 days!!! But the account is still running interest. No customer service once paid because you just have no value to the company any longer as there are no funds coming in anymore.