They rejected my id document

Just got a phone call from Passport Canada saying I need to re-send my ID document, because the guarantor signed it on the back not the front. I had another look at https://www.canada.ca/en/immigration-refugees-citizenship/services/canadian-passports/new-adult-passport/required-documents-photos.html and it doesn't say it has to be signed on the front:

• If you want to use a photocopy of your ID, make sure you show both sides and have it signed and dated by your guarantor or signing official.If you want to use a photocopy of your ID, make sure you show both sides and have it signed and dated by your guarantor or signing official.

They said I could fax it back. Does anybody have fax machines any more? They said "if you have a multi-function printer, you can use that to fax". I pointed out that you can only do that if you have a land line.