Hopefully someone can assist with the following - yes, we've asked the US Embassy but they're f'ing useless and I'd like independent information if possible 
My grandmother is half-way through a RTW trip, currently in the UK. Unfortunately she has had her passport stolen - and even worse, she's travelling on a South African passport and hence needed to get visas issued for almost all of the countries she's visiting (as opposed to an Australian passport where you can just waltz into most countries).
Her next stop was going to be France, but there's about 0% chance of getting a new passport / visa issued in time for that, so most likely she'll skip France, stay in the UK, and go straight from there to the USA (the final stop before she comes home).
She's in the middle of getting the actual passport replaced - obviously the highest priority - but once that is done she needs to get a replacement USA visa. After much screwing around we were finally actually able to speak to someone at a US Embassy (in Canberra, as opposed to the one in London), who told us there is no process for replacing a lost visa - you have to apply for a new one from scratch, which takes the normal amount of time (2-6 weeks from memory).
Has anyone had the unfortunate experience of going through this before, or knowing someone who has? If so, is the above correct? Or is there actually a process for speedily-replacing a lost/stolen USA visa?
Thanks.
EDIT: I should add that we have found the info on pages like http://london.usembassy.gov/lost_and_stolen_passports.html - that explains what to do, but isn't clear about how long it takes to get the replacement visa.

My grandmother is half-way through a RTW trip, currently in the UK. Unfortunately she has had her passport stolen - and even worse, she's travelling on a South African passport and hence needed to get visas issued for almost all of the countries she's visiting (as opposed to an Australian passport where you can just waltz into most countries).
Her next stop was going to be France, but there's about 0% chance of getting a new passport / visa issued in time for that, so most likely she'll skip France, stay in the UK, and go straight from there to the USA (the final stop before she comes home).
She's in the middle of getting the actual passport replaced - obviously the highest priority - but once that is done she needs to get a replacement USA visa. After much screwing around we were finally actually able to speak to someone at a US Embassy (in Canberra, as opposed to the one in London), who told us there is no process for replacing a lost visa - you have to apply for a new one from scratch, which takes the normal amount of time (2-6 weeks from memory).
Has anyone had the unfortunate experience of going through this before, or knowing someone who has? If so, is the above correct? Or is there actually a process for speedily-replacing a lost/stolen USA visa?
Thanks.
EDIT: I should add that we have found the info on pages like http://london.usembassy.gov/lost_and_stolen_passports.html - that explains what to do, but isn't clear about how long it takes to get the replacement visa.
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