Not that it's an excuse for them NOT to be calling you back but consider that this is their busiest time of year. And I don't know if MD had as much rain this spring as MI did but I know all the area pool builders are doubly busy trying to catch up.

Again, it would be nice if they could just give a courtesy call and schedule something but if you're going to build a pool, get used to delays!

My advice - go with a fiberglass pool.
I have had both vinyl and concrete pools before and fiberglass is the best!
Our San Juan fiberglass was a really easy and quick install and it it the easiest pool to take care of. It uses very few chemcials and I have had no algae problems in 7 yrs with this pool. With our concrete pool I always had algae problems. It also heats up very quickly in the spring. My pool is always 7 or 8 degrees warmer in May than our neighbors (same size gunite) and my sisters vinyl. I am so glad someone told me not to bother with a heater. With a solar cover we can swim from the end of April through the middle of October which is more than enough for us. We are located in Central PA. Ours happens to be a San Juan Pool but there are other fiberglass pool manufactors out there.