ONLINE PAYMENT REVERSAL

TFG set reserved R1671.30 from my account for internet purchases, but they ultimately only finalised R332.10. My bank explicitly states that TFG must conduct the reversal of what they reserved back so that it clears in my account. I now need to get the remaining money returned into my account. Bank even stated that it does not handle partial refunds, thus because TFG made the reservation, they are the ones who must resolve this situation. TFG has since given me a letter addressed "To Whom It May Concern," in which they frankly state that they reserved the full sum. They are giving me a runaround and saying they can't help me, so where is my balance now? Nobody at TFG has been supportive they all claim that my bank must sort my situation.. Im LOST FOR WORDS