A little technical stuff about DSL - simplistic
DSL stands for Digital Subscriber Line. What this means, is that your internet data from your computer to the Verizon nearest central office switch, runs through the normal telephone lines. Now, most people know this, but there are three things that affect speeds: The quality of the lines, the congestion on that specific segment, and distance from the central office which is where the internet switches live (of course also the equipment in the central office, but none of us can do anything about this).
So, in terms of quality of lines, we've all seen the quality of verizon's work, which is perhaps not always the best. There are standards in line condition for data use, and I've never seen these standards adhered to in the DR. So, if you're a little away from the Central Office, and the telephone lines between them and you are of a bad quality, you can expect to receive a much lower up/down speed than promised.
What actually happens is that the internet switch in the central office measures the error rate and quality of your signal periodically. If it is not up to standard, they reduce your allocated speed and test again .... and so on until they get to a speed that meets the standard - and there they leave you. So that is one reason why you might not get your full speed. The max distance between you and your central office for DSL is 5 km technically but any distance more than 2 or 3 km is a push in the DR based on the poor quality of the line infrastructure.
There are two things you can do - ask the Verizon Tech to test the line for data transmission. What they need to do, is to put a meter on the line, and check for the quality of the data signal coming through. If this is poor, there is a thing called line conditioning, which is a process the tech goes through to ensure that the line is in the proper condition to handle data - this means they have to fix the darn thing!. (The techs won't like you for asking these questions and asking for these services.)
Congestion - this is simply where there are too many users on that particular DSL pipe or channel. Since this is shared bandwidth, the more users, the less bandwidth per user. If your lines are of good quality and you still have poor speeds, like one quarter of what you've contracted for, Verizon needs to make more DSL capacity available. In this case you're sol and the only thing you can do, is to complain consistently, until they increase capacity.
Hope this helps somebody somewhere. BTW, Central Office is not the Verizon Office where you pay your bills. It is the physical building where the telephone switching equipment is located for your town or area.