Sort of related. I have 2 complaints ongoing.
No. 1 is home phone / broadband. Home phone is hissing, buzzing and beeping. Broadband is slower than doing morse code between two tin cans connected by string. So I call BT who agree to send an engineer. Except if its a problem on my side they want to charge £130, if not its free. Hmmm.
No. 2 is the hotel in Paris which I want a refund for. It was disgusting and EasyJet seemingly are ignoring my complaint. So I am about to ask Mastercard to take the complaint over - under UK law the contract is between MC and EasyJet, and I suspect MC have better lawyers than I have
Marketing - we moved here 5+ years ago and we still get mail for the previous owners. Mrs A used to work in the marketing database industry and regulations say that marketing databases should be 'cleaned' (e.g. No Calling opt-outers removed, people who have moved marked etc.) every 2-3 years. So obviously they aren't.
As for cold callers I find the "oh, hang on - I've just made a cuppa" and then leaving them hanging for 2-3 hours works just fine.