Edward Davey MP; saving money on postage?

I moved house in October, out of Kingston where Edward Davey was my MP, into Worcester Park (haven't a clue, but probably a Tory).

My post is redirected. I received a letter from the Post Office stating that there's a letter waiting for me with underpaid postage. Thinking it might be something important I duly paid £1.30 to receive.... a letter from Edward Davey. It had no postage at all on the envelope - but what was more interesting is the statement inside stating "Printed and delivered at no cost to the taxpayer".

Quite right about no cost to the taxpayer - I paid to have this junk mail delivered! And £1 over the odds. I went to his website on 1 December and wrote the nice balanced email....

"Edward,
I have just received your letter "produced and delivered at no cost to taxpayers". But this was after having to pay the Post Office £1.30 to find out who had sent me, my wife and daughter a letter with insufficient postage applied.
So should I have received it for free? Have the Post Office got this wrong?
I look forward to hearing from you
Scott"

Surprise! I've still to get a reply.....