Edgar's giving customers wrong info on cellphones

I purchased a phone at Edgar's in Claremont on the 25 February and I signed the warranty slip and was told if I had problems with the phone within 7days I should bring it to the store. Two days later the phone starts acting up and the speaker is not working and days after it starts switching itself off while I am on call even when the battery is fully charged. Now today (3 March) five days after the phone was purchased they are telling me they have to take it for assessment and in that period I remain without a phone and without my money. There is no such clause on the slip I signed. Edgar's must give back my money and I will go to a shop that won't lie to me to up sales!