If you work in a call centre making cold calls to people who have not invited you to call, even if it is for genuine sales or to solicit charity donations, you are being extremely rude and the same rudeness in return should not be a surprise. If you call again after being specifically asked to remove my name and number from your database, then you are breaking the law and can expect to be treated as such.
These UK companies are the reason foreign call centres ring us over and over and won't stop until you answer their questions. I was harassed every single day by a call centre based in Egypt. "Peter", "Michael", "Rachel" etc would call me at least 6 or 7 times a day. "It will only take a minute of your time madam!". I said no every time. I started out nice. I tried being rude. I swore. I wasted their time with inane questions. I used whistles. I put them on hold. And In almost every single phone call I requested that they take my number off their system.
I think they had my number flagged as a multiple calls a day number and mess with her instruction because they wouldn't take no for an answer.
After about 4 months of this shit and screening calls with my answer machine (terrible for my business) I found out they're an information mining company and head office was in the UK. They ask a load of questions about things like insurance renewals, utilities, phone, tv and internet suppliers, what washer, dryer and cooker you have etc and any reply at all (negative or positive) is them getting an invite for a UK company who buys their mined information (aka permission to call bypassing UK cold calling laws because they said the words "electricity supplier") to call you.
My final call from them came after I sent a demand to the UK company that they call their foreign call centre off. I allowed them to ask their questions and said no comment to each one thinking their info would be useless. I had 6 months of calls from every UK company out there that were even slightly related to any of the questions asked.
Call centre work is shit but it's their bosses keeping the dodgy foreign call centres going and calling you KNOWING they're bypassing UK laws. I try to be nice to them but you call me more than once and I WILL have my fun.