After Türk Telekom was privatized, it also married a company with Avea. So I think the problem is not in privatization but somewhere else.
What I remember of TT privatization in the early 2000's to KSA resulted in financially emptying the company and defaulting on the debt, so the Turkish state had to take it back, Broke, downsized, indebted, emptied.
I remember watching a video with Babacan and even posting an explanation to this a few pages back.
Many things may have happened afterwards to try rebuild the trust and faith in TT. But without transparency and accountability we won't know what exactly.
And a solid investment like communication is a no brainer. Considering the age we're in. You need to be braindead to truly fail. I can give you several examples from Denmark where a startup ends being sold for several billion USD, then the guy goes on and makes another startup and sells it too, in communication field.
In electricity too, newest start up in Denmark "Welcome" (Just in danish though "Velkommen") is already breaking down old ways of doing business and cost cutting on subscription fees and such. This results in massive new customers and turnover, the guy is a billionaire in Dubai now.
Our problem in Turkey is related to having proper investor who wants to invest in the country and not suck it dry, and leave a dead husk of a company behind.
You can only achieve that if you can get the right investor into the land. Telenor was a big loss.