Mr Price - Worse service received from mr price galleria

Good day,
I am extremely unhappy with the service received from Mr price Galleria, it is now my second bad experience in 2 months. I did a layby last year and collected items in December. On the day of collection my mum purchased a pj for me as a gift and gifted me on Christmas day obviously without a slip.... when I went to exchange it due to not liking the style even though the tag was still on the item the store refused to exchange due to not having the slip I even spoke to the manager and I asked if she could assist in locating the documents as I do not have the slip she refused...… after leaving the cash desk and searching I did find something that was purchased on the same and went back to the manager making noise and she did decide to look for the document which I could not understand why they couldn't do it in the first place. But they where very slow in assisting and very rude and unfriendly and again the same layby had a pair of sandal that that cut after 2 months which is ridiculous and now my mum went to exchange it with the layby slip they said they cant change it because they need the slip that has the barcode. where is the customer service???? Do they understand that people don't have the finance to running back & forth...….. And we are regular shoppers at Mr Price I work in morning and I receive amazing service from Mr price windermere regardless of them having a smaller range.