working fine (touch wood
layful: ) Disconnection was never a problem. Speed was, but solved. It was a problem from Prabhadevi only.
If from very beginning you are facing disconnections for higher speed, then i think its your line fault only. Why don't you check what speed you get on your line in exchange MDF ?? You should get full speed ther, with highest stability / SNR.
If the SNR in the exchange itself is low, then exchange needs to improve some things. Ask for line diversion or whatever else they can offer. but first check it in the exchange, then compare it with your place. Find the losses.