I am also extremely dissatisfied with this product. I bought 16 units and the plastic glides have already fallen apart on several of them. It used to be possible to order the plastic glides, but they have now been removed from the range. As a result, the whole set has to be bought again at a hefty price of 28. So don't bother with this system... The solution from maarc does not help. The two parts on the left and right are sturdily built (and can still be reordered).
With this panel curtain system, only the plastic glider is defective. I think it's absolutely wrong that I have to buy the whole system every time, even though I only need the plastic glider. So I pay CHF 27.95 every time for something that costs a few centimes. According to your staff, it is not possible to order these glides individually!