Bad customer service

I bought a phone from Ackermans Randurg Square on the 28 January 2021 the phone is mulfunctioning I brought it back to the store as its still within warranty I lost a receipt now am being told they can't take it for repairs without the receipt.. What nonsense is this... Y'all are quick to take our hard earned money then sell us damaged goods and refuse to assist. If I don't hear from y'all am reporting you to the ombudsman.