If you are looking for someone to cut or heat your springs to lower your sentra, you are just wasting money. I strongly suggest that you get a set of proper lowering springs made for your car.
Budget would be around P7k to P12K including labor.
If you want more advise including which shop that can be recommended, kindly advise me which area you are from.
BTW, you can also look for online sentra or nissan car clubs because you can check if they have stuff for sale that you need/want to buy.
Example:
http://www.clubnissansentra.tk