Okay, let's clear a few things up:
Compassionate/Compelling Circumstances:
I sincerely doubt that not being in the UK in time for your wedding reception will be considered 'compassionate circumstances'. Being granted a visa on compassionate circumstances is very rare.
'Compassionate circumstances' are things like:
- your spouse has been diagnosed with a terminal illness and doesn't have long to live
- your spouse or a close UK family member is on their deathbed and you need to get there ASAP to be with them for their last few days/weeks
- your life is in danger in the US and you need to fly to the UK as soon as possible before something terrible happens to you
- a natural disaster has occurred in the US and you have lost everything and are now homeless
- a civil war has broken out in the US and it is no longer safe for you to stay there
12 weeks service standards time
This is the time in which UKVI aim to get 95% of ALL settlement visas processed... both priority and non-priority. It is not an indicator of how long the application will actually take.
Depending on the time of year and how busy Sheffield is, it may take just 1 week for non-priority, or it could be 3-4 weeks, or 6-8 weeks, or it could be the full 12 weeks, or, like last summer, there might be a massive backlog and it could take up to 5 months.
Priority is also not immune to these timelines either. All that priority processing does is allow you to skip the waiting line (like a Fastpass at Disneyland). However, once your application is in the ECO's hands, all bets are off and it takes as long as it takes. If it's a straightfoward application, the decision may be made within a couple of hours, but if it's an exceptionally complicated application, if it requires more documents, or they have to look into convictions/previous bad immigration history, it could take several weeks.
Contacting UKVI
- THEY will contact YOU about your application, either to tell you a decision has been made, or to ask for more documents/information
- you should not attempt to contact them UNLESS you have gone past the 12 weeks service standards time and still don't have your visa... in which case you can attempt to contact Sheffield and/or try to get your MP involved.
- contacting the Enquiry Service is generally pretty useless, and some have speculated that doing so actually slows down your application
- the only way to actually contact Sheffield themselves is through their direct email address. However, they do not advertise this email and, as above, you are not supposed to attempt this unless it has been more than 12 weeks.
Upgrading to priority
- up until about 1 year ago, there were instructions on the VFS Global website for how to upgrade to priority processing after mailing your application. It was not advised to do this, but it was possible
- last year, VFS Global overhauled their website and took down this information. Their FAQs now state that it is not possible to upgrade to priority once the application has been made
- we all assumed this was hard fact and have been advising people not to attempt it as it is not allowed
- someone posted here last week that they had managed to upgrade to priority, despite the FAQs, and were told by UKVI that it was only possible for settlement visas now.
- that person is the ONLY person I know of who has done this... so we still don't know for sure what the official rules are for priority upgrades