Lee MacDonald, who played Zammo in children's TV show Grange Hill in the 1980s, told the BBC he has had an "absolute nightmare" following TSB's IT glitches.
Mr MacDonald, a key cutter and locksmith, told Anna Foster on BBC Radio 5 live: "I'm having an absolute nightmare. I've got two accounts, both business accounts, with TSB."
Pleasure to speak to @leemacdonald - AKA 80s TV legend Zammo from #grangehill - on @bbclive earlier about #TSB. He now runs locksmith and key-cutting business Mentor Lock & Safe Co in Wallington and his business has ground to a halt because of the bank's IT problems. #justsaynopic.twitter.com/HtbmTXKm6l
-- Guy Kilty (@GuyKilty) April 24, 2018
He continued: "My business has literally stopped. I don't know what money's coming in, I don't know what money's going out.
"It is unbelievable for a big company like that. I'm in absolute turmoil at the moment."
He continued: "I've been ringing the online helpline and it goes to an engaged tone, so I can't even speak to anybody at the other end of the phone...
"When you're running a small business, every job counts and it's just a nightmare."