I've just had very persuasive young lady trying to bully me into having a smart meter. She had an answer for everything and hinted by the end of 2020 I wouldn't have much choice in the matter anyway. She said they would phone again in 6 months time despite me saying I didn't want them to.
At the moment they're not compulsory so stick to your guns and say no. If she wont give up nust politely say no and hang up - they'll get the message eventually. As for 2020.... there are some circumstances where smart meters just wont work so I seriously doubt anyone would be forced to have one fitted.