The frame of my Barletta broke two months ago and I'd like to try and replace it but having trouble as I bought it second hand. I live in Ireland so can't buy one either.
I am sorry to hear that, Apart from contacting any seller that actually sells or delivers the Riko brand strollers to your country, you can only directly contact the manufacturer, here's their contact page.
These cheaper Polish strollers are often hard to get spare parts by. So be patient, try, but be prepared your problem might not be solved.