Spectrum enforcement does happen. It usually takes a while to identify because there's usually not a large noise source or illegal transmitter. Instead it's usually malfunctioning equipment that's doing stuff it shouldn't.
Usually how enforcement happens is that someone complains that this one spot never gets a signal, or their phone always cuts out. Then the big players start getting involved to determine the problem and either get the fcc involved if needed or otherwise inform the offender to get I fixed.
Don't contact the FCC directly. Contact your cellular operator. They can investigate to see if it is a problem on their end. They will also contact the FCC if necessary.
Usually how enforcement happens is that someone complains that this one spot never gets a signal, or their phone always cuts out. Then the big players start getting involved to determine the problem and either get the fcc involved if needed or otherwise inform the offender to get I fixed.
That's how stories like this happen, https://www.engadget.com/2016/05/25/florida-man-fined-48k-fc...
EDIT: to add there's a lot of unintentional interference sources, neon signs are a typical culprit as they age, http://www.signindustry.com/neon/articles/2004-02-16-RadioFr...