Family Dollar complaint: customer service

My 17 year old decided he wanted to go into the store to look around he didn’t have a face mask so decided to ask if they had any. The associate that answered him questioned him what was he going to buy. First of all it doesn’t matter if he is going to go and buy something or just look around. My son asked again and all she said was no so my son decided to leave. When he told me I did call the store and come to find out this associate was suppose to be a supervisor. I am too an HR Supervisor and at no point do we ever coach our associates to be asking any customer what they are going to purchase before we let them come in or answer their questions. I think her being a supervisor needs to understand that you don’t do this regardless if the customer is young or not. When I was complaining to her all she had to say was that it was not meant in a wrong way but my son came home feeling like she questioned him because he was going to steal. I believe your supervisor at this store is in need of a little bit more customer service training. I know for sure we are not shopping at a family dollar again to get that service. Like I said I did complain to the store but all she had to say at the end was to have a good day and hang up on me again not good customer service.