It's not the "Time Remaining" that increases, but the data of the battle (map, mode, etc.) that slightly increases as more players join before you and perform actions. Sometimes, gold boxes dropping shoot the number from ~ 200 to more than 270. 
Keep in mind that this will always happen for the first few battles. I uninstall the app during the periods I don't play, and I have seen this happen everytime I join my first few battles.
So, my advice would be to stop reinstalling the app or clearing the cache and let the game properly load. Better wifi definitely helps. Let the quick battle button find a battle, let it load for a long while till it reaches a very low number (1 preferably). By then, you would have been timed out for inactivity. Close the app (using that button on your phone that shows the list of running apps), then restart the app and try again to join a battle. Most probably, you'll enter it. If not, repeat the procedure until you finally get to play.

Voting a question or an answer means that it's a good/helpful reply or question. Answers with the most votes (most helpful) appear first on the list. [Unless 'sorted by date' instead]
Only Advanced members are allowed to up-vote questions and answers, hence you're suddenly able to do so.

You need to complete all the other missions and the reward will unlock by itself.

Question of the Week Submissions

Please clear this out:
I suppose you're talking about Forum log in, and that your account has been duplicated due to the forum update, as was the case with many others. In that case, contact @Maf via PM to merge them and continue using this one for the while (no content you post will be lost).
Or, if you're having issues with logging into the game, then please elaborate your problem.

There has been this bug on the ratings page for quite a while. Ever since the site came back up, after the Modification update, it doesn't record any experience earned with a turret into the respective achievement. I've earned over 50k exp with Gauss but the achievement still shows 0 progress.