Appalling service

My experience has been great in the beginning, I then eventually managed to pay up debt and was advised that it would take 3 weeks to receive clearance certificates. Debt was paid up in full March month, but there was a mess up with one of the accounts. I was told the lender would sort it out by the 11th April, I followed up to find out that the lender can not do it. At this stage I called to try and resolve the issue, but ended in an argument with the consultant as I was now at fault for the delay. It is now a month later and still hasn't been resolved and I'm constantly following up and getting told it's being looked at and every week it's the same thing. I get no feedback unless I get in contact. I am appalled at this level of service as this is an issue that could have been resolved within a week and yet it has taken 2 months with no success