Capitec withholding my money on my flexi account refusing to release it.

Capitec refuses to release my money from my flexi account, they are allerging that they were instructed by SARS to withhold it. They are refusing to give me the letter of instruction that they received from SARS. I wanted to take the letter to SARS to have the issue resolved. I visited the branch in Port Elizabeth Govern Mbeki branch today was the 3rd time this year for the same thing.I visited SARS Port Elizabeth branch and they said they didn’t give any instruction to Capitec regarding my account. I need help