When I cycle my bike makes a clicking sound. Also when I change gear it won't change the first time I have to keep putting it back to the previous one and back to it and eventually it will change. Also when I put it into gear 1 the Chain will come off. This started happening weeks after I brought it I went back to the shop as it has a 12 month warrantee but they said it's not covered under the warrantee as it's wear and tear
does anyone know what the problem is and is it an easy fix or do I have to take to a repair shop?
There are two types of "warranties" - the manufacturer's, which is against manufacturing defects, and a shorter "free adjustment period" or "30/60 day check," which is meant to address exactly your type of issues and is essentially universal in the bike industry. If the shop assembled your bike they would normally be obligated to address the issues. You need to ask if they have a free adjustment period and if so indicate you will complain to the BBB and publicize their poor service if they do not fix the problems. If they still refuse or do not do it properly contact the manufacturer (they may refer you to a distributor) to lodge a complaint. More info on the type of shop and brand of bike would help greatly.
DO NOT yet attempt adjustments yourself or allow anyone other than the shop to do so as of yet. Your wisest option if they will not fix the problems and you find that they have an adjustment period or their agreement with the manufacturer/distributor includes that provision is to have the bike fully adjusted at another shop and take them to small claims court for the cost of repairs. It would cost you up front, but with sufficient documentation you would have a strong case.