Call centres often seem to have a script and they only give answers from the script, even if it doesn't answer the query. In some cases, the person on the phone is only employed to answer the phone and another department does the other things, often in another place and there can be a lack of communication or a delay between the two and this affects the customer.
I've worked in retail and hospitality for a few years and I honestly believe if someone has had bad customers service, they likely deserve it. I know some staff are rude and can have a bad day and some staff are shit at their job or do the wrong thing so nobody is perfect.
However, customers are more entitled now. The normal behaviour we see is quite impolite ( eg talking on their phones while being served, putting their shopping on before previous customer moved along , interrupting to ask their question while someone else being served) .
The majority of complaints we get are because a customer has been told no , because of what they want is against our procedures (eg our apple pay in store is limited to a £50 transaction, or we can't give a discount because the goods don't belong to us as they are sold on behalf of supplier). It's often their expectations that are the cause, not our service.
We say 'The customer is not always right, the customer could be lying or mistaken '.