Building unit in basement zoning issue

[Luis Melendez]

Hello Fellow real estate investors. I need some advice on a property I have in Bristol Connecticut. 

 The property is a 3 family zoned in a r-15 which means single family/mixed overlay zone which only allows up to 3 units in that zone.

The property I have is a 3 unit but has a basement that is PERFECT to add another 1 bedroom unit.  It’s has a great layout, high ceilings, ABOVE ground with windows, 2 paths of egress. 

But since it isn’t zoned in a MULTi FAMILY the town says it would be an “uphill battle” to Rezone to allow a 4th unit. 

My question is has anyone had success rezoning and was is as hard as they make it out? And if you had success what steps did you take and advice can you give to make the process easier? Any advice would help. 

Thanks