Please donot waste time on the inquries. Those at the CIC call centres are not always "informed" and would not entertain specific questions in details, resulting in often rude or cold replies. You would drain your head and ruin your day doing nothing but getting depressed by the treatment you got.
As mentioned. Do exactly what the letter you received says. If you beat around the bush you're complicating and delaying your case. After all this mess do you think its GOOD idea to waste more time until new tough rules show on your doorsteps like say in few months?
Also next time give all the information. Yes its understood that you add copies of all stamped pages/visas you ever got when you apply for an immigration. You seem to be a genuine applicant. Just comply with CIC letter and you would be in canada in no time. Make sure you provide all documents + a letter with explanation if needed on issues you're not sure they would understand while processing your application. The more information you provide them the better. If they discard information that's alright
also note you donot have had to sit in IELTS if you had attached a certified letter "form" all schools + workplace etc that the medium of education was in english. If you ever worked in any position dealing with public eg. customer service, checkout operator etc etc. you could have mentioned that as well. This is enough to prove that you're comfortable with english language. They donot always want your stories unless backedup by stamped paper document. BUT now since they've already asked for IELTS scores, IMHO you comply with that intead of letters, because it might look like you're avoiding test.