ackermans phones are ****

i bought a Samsung A21s beginning of September from from bopedi store. It started flashing the screen and cutting calls 2 days later, i returned it, they gave me a new one. 10 days later it started the same problems. Took it back to the store, they took it for repairs . Collected it last week, 3 days later it started again. Now i am evin beginning to think ackermans sells **** phones . I am really frustrated