Courierit poor service experience..

On 24th June2024 I've requested for a return of my package due to size .so courierit promised to come on the 28th june 2024 and indeed they come as promised and collected my parcel back to the seller (Converse Sa) without even me signing any form to show that the parcel was collected. So now I'm having a problem of which the was no confirmation of feedback nor any progress on my parcel if the seller has received the parcel yet. When I call converse Sa they tell me that the problem is with courierit when I call courierit they say they are still looking for my parce and it's been 2weeks now and now I'm starting to lose trust if my issue will be dealt with .so please help me anyone.