Hello,
If you did register with the manufacturer during the designated period in order to benefit from the offer, then a certificate of extended warranty should normally have been sent to you by e-mail.
Maybe look at the warranty certificate or copy it and email it to the company, I think they will do a warranty extension, have had the same coffee machine for a few years and it works great for us.
The ECAM 350.55.B is supplied with a Swiss power plug. Concerning the international warranty you can directly contact Kenwood:
info.swiss@delonghigroup.com
+41 (0)41 766 87 27