Recommend a Friend - and get a bad service

Recently we changed broadband supplier. Everything was going great until today when we have a large direct debit taken from our account. Called the supplier and it appears that the cowboy who came to the house to sell us the broadband has mucked it up. Here's how the story goes; A friend had an email to recommend a friend to the supplier, they would get £50 and the friend would get free installation worth £40. Our friend followed the instructions, gave our details and the company said they would call us to arrange things. Despite getting an acknowledgement email from the company, after a week they still had not called us. During this time the company had put a flyer through the door with the local sales rep's details on. We called the rep and he came round and signed us up. He was made aware of the recommendation, given the details and the reference number and said he would sort it. He signed us up for 18 mths ; 6 months at £23.00 then 12 months at £29.00 - all confirmed in writing on the contract .Activation/installation/other charges he wrote on the contract as NIL. So today when we queried the DD we were told it was made up of £23.90 x 2 and installation of £40. According to the supplier we are signed up as 6 x 23.90 then 12 x 33.90. We have to pay £40 installation fee plus the friend doesn't get the £50. They want to see a copy of the contract we have signed, strangely for us to send them OUR copy. We are sending them a photocopy of OUR copy - whats the betting it would get lost in the post etc etc. I am so annoyed.