Customer who's trying to exchange size only

I went to the Cornubia Truworths yesterday ( 21/08) to exchange sizes of 2 t-shirts purchased for my husband for his birthday, however I had no receipt but all tags and stickers where intact. I was informed that I could not be assisted as there's no receipt even though it was for a size exchange. I called for the manager, hoping there could be some assistance as I'm not asking for cash back ,I just wanted a size swap so my husband could use the shirt for his birthday tomorrow. Hadsa the store manager simply said there's nothing they can do to assist me as I dont have the receipt. So today (22/08) my husband had to leave work to fetch the receipt from the person who bought it and then go to the same store to proceed with the exchange. Now the store is saying they can't help as it was bought on account and the account holder isnt present!!! This is quite frustrating really. Why is this store being so difficult? They asked for proof of purchase and now when its produced they still can't assist!!! I'm really disappointed with the service I've received. Apart from the unapproachable store manager who talks like she as no energy what so ever and not even a smile to acknowledge the customers instore is really upsetting. I've received such amazing service from the Gateway branch that you actually do feel welcomed. Perhaps someone more senior with a bubbly personality towards her customers is want the store probably needs. So now I need to know the way forward as the account holder is unable to come to the store other than next week and I need the correct size shirts ASAP. Please can someone rather contact me as this is urgent.