Vehicle finance application dragging for 4 weeks

My private sale application was initiated 9 March and since then it's been an absolute nightmare to finalise. I had to beg to get a pre-agreement quotation with the correct information since the 11th and finally received it on the 24th after numerous requests. All the necessary documents were sent in by the 19th but the contract was only ready on the 24th. Contract was signed on the 25th and on the 27th I was informed that a new settlement letter was needed since payment didn't go through on time on the 27th. When I had to sign the contract, I had not seen it yet (apart from the pre-agreement quotation), and I still have not received a copy of it. I understand that private sales take longer, but this is ridiculous, it has been almost 4 weeks. I also had to get 3 settlement letters because of the delay. I am sure that this is not standard practice and would appreciate it if someone could contact me because I am extremely unhappy with the way my application is being handled.