Recovery of maintenance charges of flats and shop

We had a land on which we did builder agreement on the ration of 60 & 40 and the construction of apartment completed in 2010.there are 4 flats and a shop on ground floor we sold out 3 flats and shop and in remain 1 flat we reside.There is no society in apartment and no one is ready to make society .since the time we sold flats and shop .the purchaser of flats and shop is not paying a single penny for maintenance charges since the time they purchased the property.we are bearing the charges of sweeper and the electricity of submersible motor.The condition of building is getting worse in the lack of proper maintenance .We ask them many times for maintenance charges but every time they made lame excuses and do all possible way so they don't have to pay the maintenance charges.Kindly help me out and tell me a way through which i can recover the maintenance charges from them from the time of their property purchase and none of them can rescue their self from paying the same.and also tell me on which ratio I should take maintenance charges.