Terrible service

I had the most shocking experience at this water shop at hunters retreat shopping complex in port elizabeth. I had bought and paid for 10l of water and had asked one of the shop assistance if they wouldn't mind carrying it to my car. The shop assistant was busy walking out when the owner took the bottle from her, while walking behind me and my elderly parents in the parking lot the owner starts yelling at me asking why can't I carry the water myself, I said sir because I have a bad back and recently had a procedure so I cannot lift heavy, he proceeded to scold and debate with me in the parking lot that its only 10l not 20kgs I said to him 10l is 10kgs and if you were medically inclined you'd know that after any procedure you're not supposed to lift heavy, he continued to scold me saying it will not be done again because his shop is busy, I said based on your rudeness and attitude towards a paying customer I don't think I'll be back he said o you not buying here again then fine. I mean if this is how small business owners treat their customers then want to know why they don't get support. Apparently I'm not the first person that has received rudeness from this shop.