Waiting for clearing confirmation email? Running out of time

Hi I got accepted into 2 clearing options, 1 is better than the other and they've just come off clearing in UCAS. On the phone they said I am accepted yesterday, then I called today and was also accepted.

They have said they will email me, but I have been waiting, my other clearing offer is about to expire and has emailed me but is much lower than the one that I want and now it is also off the UCAS site. The one I want did email me about an open day but nothing about continuing to UCAS. I tried ringing both seems they're now closed till tomorrow. It's going to be a rush decision what would you guys do?

Would I be able to cancel my clearing entry after submitting? Say for example to make sure that I don't lose out on both I then go to apply for the other one a few hours before it expires?