I put new springs on my car last year as they was an mot advisory 

  But they are soft I have put spring assistors in them and they are still soft to day I picked up my pigeon feed order 8x25kg bags put them on the back seats and the tow bar is nearly on the floor  

   Is they any up rated springs I can buy ? 

Had a quick look on KYB catalogue  but no heavy duty ones but  Fabia came as a van and as an estate as well as a hatchback so the springs I assume would be heavier duty on the van and estate My folks had the estate and never had a problem with weight and they loaded it to the max.  Are you sure the ones you got are for the estate and not the hatchback. Another point would be the rear shocks as well. Have had cars in the past that sat low due to failed shocks.

 

KYB RH6085 - fabia mk1 hatch 1.9tdi

KYB RH6402 - fabia mk1 estate 1.9tdi

KYB RH6086 - fabia practic 1.9tdi

KYB RH5537 - fabia practic heavy duty 1.6tdi

Not sure if the above would be interchangeable but the heavy duty ones are thicker at 12mm instead of 10mm

You would need to find the dimensions etc

Alasdair

 

 

Found this on parts in motion website

RH6085 341mm length,99mm dia, 10mm thick

RH6402 343mm length,96mm dia,10.3mm thick

RH6086 342mm length,96mm dia,10mm thick

RH5537 364mm length,111mm dia.11.8mm thick

Can't guarantee the above is correct as its just pulled from a website and not the manufacturer. I once changed the springs on our old fiesta and was sold the VAN version  without realizing. It ended up looking like a hotrod the rear end was so high and drove like a spacehopper. It was hilarious to look at and drive. Might be worth trying RH6402 as their slight thicker and just slightly longer depending on what you have fitted. A quick phone call to your local skoda dealer as well and see if there is an oem heavy duty option or what should be fitted to yours. As said folks 1.9tdi ambiente must have had HD springs as they carried a huge weight and never had a problem. 

Thanks I will have a look am sure I put lots more in my old estate and didn't have a problem