Welcome to Scamwarners, and thanks for letting us know it helped you.
Toybox
I need to warn you that it only gets worse from here.
I was the victim of such a scam, I had an email from Willem also at the same email address you wrote about - but this was after I was scammed by somebody else - I'm sure it's the same guy as the phone number he used was the same phone number as you posted.
I can give you the details later, but the person had used a Scanned Passport of a European (emailed to me as 'proof' that he was the European person).
I found out later that it was really not him - he had obtained such a scanned passport via the method you described - by people sending the Scammer their passport copies to get the apartments.
So - you are now the victim of Identity fraud.
In my case, the scammer had used an +44 0702... & +44 0703 number - which I later found out were 'platform' numbers - and although they purport to be in UK they are not (although not the same scam, read this to find out about the phone numbers from UK Police - Right click and "open link in new window" to remain on this page (met.police.uk))
So if you have sent them a phone with a SIM card, they simply use that phone to carry on with the crime with somebody else. I'm afraid it's sad, but true.
I eventually found out all this by searching online and found the following useful websites: Right click and open in new window chicaneryconsscams./ and Right click and open in new window chicaneryconsscams. .
The email address that the scammer used was on this list - the other email he used was not, but I've asked them to add it to the list.
So the scammer is now emailing people, purporting to be you - emailing your passport around as 'proof' that they will get the apartment. In my case, the scammer had even opened a UK bank account in the same name as the passport holder - and I transfered money into it, as I didn't trust the Western Union route as there was no traceability.
I contacted UK police who were not helpful at all - but have yet to contact Singapore police . I do not know what else you need to know, but please be aware what is going on with your Passport & Details.
Added instructions to links for visitors wishing to remain on this page - Ralph