Vehicle and asset finance trouble

I app**** online for a vehicle loan , got pre approved and we started the process , after a long wait for feedback I called the helpline and they directed me to a agent that tried to assist me but couldn't. So here is my problem I am getting rejected as the bank claims the company didn't deduct my PAYE but I was on maternity leave and my yearly deductible tax for the book year was corrected by the payroll system SAGE as this is common when returning from maternity leave to have a tax that is negative or 0 . This is how the system works it out this is what my accountant explained to them and even after sending through my tax compliance certificate they declined my loan because the say I did not pay tax. I don't know who to contact anymore as I am a standard bank client for years now, I don't believe I have ever dealt with such incompetency and failure to just get feedback after sending email after email. I hope that somebody from the bank can assist me with this matter.