All these people have given you the correct answer, I simply want to add something small;
Depending how far along Mexico you are (For example if you are near Central America, It is more your location not your internet Service Provider that is the problem. This is the reason why Central and South Americans have such high pings, Simply due to the fact that the Servers are too far for much to be done about it.
If you are near the Mexican/American border or even near Central Mexico then you may want to see what Internet Service Providers are around you and read reviews;
Category:Internet service providers of Mexico - Wikipedia, the free encyclopedia
(Just a list of course there are more that you know about)
Also, It might not even be that the Internet Service Provider you have is bad, But simply that there is a problem with your connection, It is always recommended that you call them for maybe a needed upgrade on your service, Or any issues that may be occurring with your current package. Best way? Find their Phone number or other contact information online or on any Bills you receive from them.
Also, I just read your last post and that sounds like behaviour that an unstable internet connection or other programs may be causing. Please make sure first that you are using programs such as SmartClose or simply Ending Processes (Via Task Manager) That are unnecessary. If this does not improve it at all please contact your Provider, There may be an issue with an unstable network. Oh, Also if you are using a wireless connection this may be the problem, If possible try to connect directly into your computer with the provided cable. If you are giving internet to more than one computer, Make sure they too are not using unneeded programs while you are playing, they could put a strain on your computer as well.