IPhone 4s lock screen button/On and off button?

IPhone 4s lock screen button/On and off button?

If you are asking of the on and off button is also the button use to lock your phone, then yes.

What is the question? If you're asking where is it then it's on the top of your phone opposite to where the headphones go in. If you're asking if that one button does both those things then yes. It also silences and rejects calls too

Well, take it back to the place that did the bad replacement,
under the sale of goods and services act, they have to put it right.

If it had been apple, (140 pounds out of warrenty costs)
you would have had a nice new shiny phone fully checked from top to bottom and a new 90 days warrenty. - and if (unlikely) it was faulty, a free replacement/fix.

either way, what is the issue with getting it fixed properly?