Contract Discrepancy - Constant debit orders

If there can be minus stars I would give it to them. I had a debit order that fell on the 25th of every month. My salary only came in on the 2nd of the month following so it cause some problems of constant rejected debit orders. I phones them and they changed the date to the 5th. This was beginning of last year. They still continued to debit my account on the wrong day. Either on the 23rd or the 14th of the 31st of a month. I called again, they lady assisting me changed the date to the 5th again. Yet there were no changes in this. December I missed the payment that went off and made the payment via the client portal on the 2nd of January. There were two more debit orders deducted from my account also incurring rejection fees etc. I called them last week and they answered telling me my account is up to date and I don't have to worry. They had to give my account over to collections because of my missed payment but they did receive it so will call it back ignoring the fact that I asked multiple times about the extra fees on my account. They didn't even deduct the correct amount according to the contract. This week I keep trying to call them but all turned out successful excluding Monday where the lady told me the billing department is offline I can call back in 2 hours time. I called and no answer. I have been unsuccessful the whole week, waiting in "queue" for up to 20mon at a time with no answer. They deducted money from my account again today and I am just fed up and don't know what to do anymore.