Unauthorized reservation of funds

I had paid a merchant for services supp**** with my debit card. The merchant speedpoint declined the transaction and I received 2 incontact sms's which showed that an amount of R8817.40 was reserved and the other that the amount was reversed. Swiped my card again successfully. Merchant got paid and lo and behold FNB still has the same amount reserved on my pending debit card transactions and I have now tried for 3 weeks to get the bank to release the funds that are *******ly reserved with no success to date. Call centre agents advised to submit a dispute form which I did and numerous calls, e-mail corersspondende with Relationship banker yielded no results. All I am asking from FNB is to resolve this matter since I am really at the end of my tether since my funds are held back by the back without authorization. They tried to blame the merchant and basically there seems to be no motivation to resolve this and I just want the bank to pay my money back into my account, which FNB I's withholding and not the merchant. I have sent FNB all relevant documents and repeated my issue numerous times with various people and I just want this addressed before I close my account