Ask them to call back in hour or day and go check out the info. you can check it on your phone
If it sounds legit then carry on the conversation and establish enough information to give you a good enough report to the police should things go pear shape (break-in or abuse is the first sign)
Ok if everything sounds good then take up the offer and fill in only questions necessary to establish a contact. DO NOT give ID or address to them until they have emailed you document to see what you are signing up for. SO DO give them an email address.
You read the email and talked to them on the phone insist on an official visit either you to them or them to you. DO GIVE an address or ID at this stage so you can get what you want. This is to sign papers sent and to an establish bonafide reporting station should something go wrong.
When your signature is on the document then and only then do you put your home address and ID.
Any application should be done like this.
Where an office is not available a commissioner of oaths acts as the office. Commissioner of oaths can be the local post office, police station, bank,SARS (Receiver of revenue) or lawyer.