l see from the many previous posts that this is not a new topic and many others have experienced this issue.
EE, Medellin is the second largest city in Colombia and your partner, Movistar, provides a great service on local sims. You clearly have a technical problem with your partner, and have not resolved it for a long while (posts about this go waaay back).
REALLY? Please get it sorted, this is mad that there is no roaming in the middle of a city with over 3 million inhabitants.