Apartment common fund

Respected Sir, Need legal advice regarding a prevailing issue in my apartment. A lengthy one please be patient in reading. When we bought the flat we came to know that some common area not shown in the plan has been sold to some of the flat owners, and that area was kept solely for them using a grill(plan is such that others need not have to go that side except them). But that every other member has paid for that area shown as common in the plan. We asked for compensation from the builder in the general body meeting several times, initially he was reluctant to pay back any. Then our apartment president, secretary along with few flat owners went to his office and settled for an amount of 6L. This is conveyed to us that builder is agreed for 6L and we will use it as apartment fund. We were been asked to give the money that is being due to builder to make up for the 6L. I paid my due that I have to give to builder through check to the association account and got the no due certificate through my apartment secretary. Some flat owners before paying the dues to the association put up the following request. Since there is no immediate need for a fund of 6L as we got lift, generator and uninterrupted water, asked to refund some amount and keep some amount in the fund. The president, secretary and few flat owners (those went to builder)didn't agreed to refund at all and say we got the deal from the builder, you have no right on the amount and the collected money should be kept as the fund only. Meanwhile we even saw some discrepancies with the maintenance of the secretary too, so we thought instead of fund we should spend money on need basis. Since they are not agreeing to refund any amount some flat owner who asked for some refund didn't paid their dues to builder to the association account. One fine day since this is not going to work secretary withdrew the collected amount from the association account and paid back the dues only to the flat owners(who went to the builder at the time of settlement). The reason he gave is that they don't want their money distributed across other flat owners. The flat owners who went to the builder for settlement are having higher dues to the builder one even 2.5L. But my money and two other guys money has not been given back. They say that they provided the no due certificate from the builder, so only if I give back the no due certificate then only they will give back my money. We are total 15flats. We want to know what right we have in the compensation given by the builder, how to get back at least my due to builder i.e 15K and other two 40K and 50K. Appreciate your help. Thanks Pradeep.