Appauling service from Account dept

I did my Down’s syndrome test via lancet last month and the guys that assisted where kind enough to advise me that I could pay my amount in 3 months instalments, which I opted for and gave the 25th as my debit date. End of the month my account wasn’t debited and I recieved a text stating that I was owing. I called the accounts department TWICE to report this and asked to set up a debit order for these payments. BOTH agents told me they couldn’t set up a debit order and that someone would call me back to assist with the debit order. I’ve been waiting since. The accounts department/ finance department service is appauling to say the least. I waited on the line for sooo long for someone to lie and tell me I’d get a call back!!