I've been with a telephone company called Movistar for years, from a time before we lived here, on a pay as you go card. Movistar have never done anything bad to me but I liked the look of a company called Yoigo. So I went to the Yoigo shop.
I was told that the phone I fancied would be 179€ rather than the advertised 49€. The price was the same if I wanted to keep my number or get a new one. The 49€ only applied if I wanted to move from a contract (rather than prepay) with another supplier to them.
I decided at first that 179€ was too much so I abandoned the idea but overnight I changed my mind and went back. This time I was told I would have to wait a couple of weeks for the number to be transferred and they wanted to charge 10€ more for paying with a credit card. I said that I would leave it.
I went to the nearest Movistar shop and got the phone I wanted and I kept my old number all for 79€.
Now I'm in the process of adding all my phone contacts again as the numbers were stored on the phone, rather than the SIM card, and not backed up because the phone wasn't that sophisticated. If you never hear from me again you'll know why.