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Of if you're planning on getting an extension done in the near future.
If you are then the Party Wall stuff is there to allow you to get the right foundations put in that take into consideration your future work (you would have to contribute to this). The idea is that if you didn't do it now (whilst they were having their work done) it'll cost you even more in the future.
But, as others have said, it sounds like a cold call from a company looking for planning applications and sending speculative offers out. I'd take it round to the neighbour and let him/her know that you're not going to cost him unnecessary money, that'll be worth some brownie points with them.
Unless they’re digging deep foundations or something, I’d have thought it’ll be a waste of both your time and their money.