The doors unlock sometime before the end of the following quest, Rescue from Fort Neugrad, or Reunification of Skyrim if you have sided with the Imperials.
I thing you are just a bit unlucky. !!!!!
I have completed all the companions quests, and i am now on the Throat of the World with Paarthurnax. I even got my house at Lakeview Manor.
I am level 30 on a 8.5 MB save file.
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I only encountered one glitch so far in Riften, with this job that i should collect money from three different people. (I don't remember exactly the quest anyway)
I reloaded i previous save, did it again, and boom all working perfectly again. !!!!!
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You should make many saves. I do 10 every time i play for a couple of hours. (I save those files on a external HDD, and i delete all saves from my PS3 HDD except the last two)
If you make many saves, and load those while playing, all those saves going the the memory right away. And PS3 memory is very crucial for skyrim.
And all your game progress goes straight away to your save, so to your memory - unfortunately. !!!!
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So keep in mind to make more saves. At least one before every quest. It doesn't matters if it's a main quest or a side-quest. !!!!!