Extra Payment on account not allocated to account

I made an extra payment of R5500 to my Builders account on 4 Nov. When I received my statement of 12 Nov, the payment did not reflect. I sent them the proof of payment and on 1 Dec they sent an email to tell me the money has been allocated to my account. I did a balance check this morning, just to see that the money still doesn't reflect on my account. I phoned them and they said that the money is there, but because it is a big amount, they must first launch an investigation before it will be taken off my outstanding balance? Really? Investigate what?? I paid extra, what is there to investigate? AND On the 4th of Nov I phoned to get a settlement on my Game account and paid the whole amount immediately. Still on 4 Dec, they deducted my installment of more than a R1000. I phoned them, no payment reflects I must send proof of payment, which I did, now to see how long it is going to take before they refund my installment. This is the worst service I have ever received. These guys are pathetic. If you have an RCS account, be very careful, they will take more than their share. *******!