As mentioned before I decided to drop Text Link Ads when they told me that my nofollow modification to their Wordpress plugin was in violation of their ToS and that my account would be suspended if I didn't comply.
Yesteday I got a new email from them, again explaining that my ads wasn't showing at they would have to suspend my account unless I re-instated them. Clearly communications internally in Text Link Ads hasn't gone the full circle and the second representative that contacted me was unaware of the earlier conversations.
I took this opportunity to, yet again, ask for the ToS that I'm in violation of and got a Word document in return. After asking yet again, I did get a link from them to the ToS. The document is only linked to on the signup page and it's not possible to find a link to it after you have registered. Why they make it so hard to review after you sign up is beyond me, but I guess we can all speculate.
Either way, the Text Link Ads Terms of Service document does have an URL, it's just not well linked to anywhere, but here it is Text Link Ads Client / Publisher / Affiliate Agreement
And yes, I was clearly in violation of it after I did my changes to the plugin, I just had no way of finding out before I decided to "hack" the code.
9. EXCLUSIVITY PROVISIONS. A. The publisher is not permitted to alter the ad script provided by the Company in any way without written consent from Text Link Ads while delivering the advertisements. ...
So there it is. No modifications are allowed.