Possible to use a device that allows the phone line to be extended upstairs through existing power wires? You insert the phone line into one end, then plug that unit into an outlet. Then plug a receiver unit into an outlet upstairs that can be used just like another phone jack. Like this - {Link}
Not sure if this is/was an option for you, but I know many people that use them with great ease, success (here in the states).
Possible to use a device that allows the phone line to be extended upstairs through existing power wires? You insert the phone line into one end, then plug that unit into an outlet. Then plug a receiver unit into an outlet upstairs that can be used just like another phone jack. Like this - {Link}
Not sure if this is/was an option for you, but I know many people that use them with great ease, success (here in the states).