Truworths staff does not know what customer service means

I bought a cellphone on 12 Feb 24, took it back on 18 Mar 24 as the phone became faulty. The shop assistant told that it would only take a few days for them to repair if it can be repaired...It's the 30th of Mar 24 and they can't tell me what's happening with the phone...no courtesy call nothing...i went to the store and their response is they don't know what's happening with the phone as MTN hasn't come back to them...my question is if MTN hasn't come back is it then not your duty to go and nag them for info...even customer care told me blatantly there is nothing that they can do and they don't even have the technician's contact details...i have no more words. This is quite disappointing as i need my phone for work purposes and they just seem unbothered but i have to pay my account.