a message popped up on my screen saying my number was chosen at random this aft in Cowdenbeath's (Mobile) prize contest and I'm now eligible to choose 1 of the 4 prizes listed below. An ipad mini was the only one still in stock. Sure it's a scam but how does it work?

Next stage will probably to "register" your details: name,address, etc. Then they'll try to persuade you they need to "authenticate" your I.D, and ask for your bank details. Either that, or you'll have to ring a premium rate line to "claim" your prize. Which will be VERY expensive, and probably go on waffling for ages,teasing the prize and directing you to ANOTHER number. The initial message is the "roper", the rest is the "convincer" and so on. A good rule is this; if you never entered a contest, you haven't won it. Companies who run legitimate prize competitions do so by targeting their real customers, to promote sales. They have no incentive to randomly pick strangers who have no interest in their products and services.

that's what I suspected - thanks, Bagsbunny, stopped me before I did something foolish. They had all these letters from satisfied customers, looked genuine but I had my doubts. Thanks again for replying.

Legit letters from customers obviously.

If it came from a normal looking mobile phone number, rather than being from an identified sender, then forward it to "7726" to report the number to your network as a spammer.

http://www.moneysavingexpert.com/phones/stop-spam-texts

Yup ! Total scam.....never reply such messages or email.