Replacement upvc door handle springs are available and by and large are fairly generic. The important thing to check is the size of the cassette units and the space inside the backplate of your upvc door handles. As long as they fit reasonably snuggly then it should do the job. When purchasing upvc door handle springs there are two options available. A single door handle spring or a double door handle spring. One is not necessarily better than the other but the size and layout means you may have to use one type over another.
The basic design of replacement upvc door handle springs is a cassette with a central spindle hole. If you watch the video you will see this is very easy to fit. All you have to do is simply slide the spring unit over the spindle and into the backplate of the handle. If they are Hoppe handles then use the single spring as this spring unit is made by Hoppe so will be a good fit.
A word of warning when it comes to buying replacement upvc door handle springs. Not all upvc multipoint door handles can use them. The reason is some handles like Fab & Fix upvc door handles build the spring units into the backplate. This means you won't be able to get them out of the plate and if you do then the cassette cannot fit into the handle. Some handles just can't take the spring cassettes anyway due to design. You can check this by reviewing the inside of the backplate which will require a certain cavity size. Do check the diagrams for both replacement springs.
If you want to buy replacement springs for your handles please follow the link here: upvc handle springs