I would like to get the following phone...
Sim Free Apple iPhone 5S 16GB Mobile Phone - Silver.

The contract on my current phone has finished and I went to a local store which sells second Hand/refurbished phones with a years guarantee..What I want to know is if I bought one of these phones and put my sim card in it would my monthly bill still be the same and what about usage limits.At present I am with Tesco Mobile and only pay about £13 per month.

I think you would have been ok with the black iPhone 5S, but I think they will charge extra for using the silver one.

....only joking.....

I believe your SIM plan price should stay the same whatever phone you put the SIM in (as long as it's not a phablet (over 7" I think it is) and the phone company notice).

Mark.