Don't just replace it, assuming the new clutch is at fault. Proper diagnosis is the key.
A Google search for Transmech gets lots of forums, but no info from the company itself. For me that would be a reason to walk away, but could be a Euro 'own brand'.
Not so long ago it was popular to recondition clutches. Only the gentlest used were really suitable for this, but there were many reconditioners that would tidy up worn components and make them look good, although most would perform badly. Are Transmech reconditioned? If new, the prices suggest they are sourced cheaply, which is never a good idea with a clutch. However, if every one was bad, they would have ceased to exist by now.
Clutches are easily damaged if dropped. So don't accept any box showing signs of damage. The cover, if dropped from waist height onto a hard surface, can lose tension in one or more of the blade springs that keep the pressure plate in contact with the diaphragm spring. If damaged in this way, the result can be judder on take up, or a sudden grip.
The centreplate can be damaged if the gearbox is hung on it during fitting. The gearbox must be properly supported until held by some bolts. If the centreplate takes the weight of the box, it bends, then will give a sudden take up. A centreplate damaged this way will often tear itself apart quite quickly as it flexes.
The gearbox must be directly in line with the engine. The gearbox will locate on at least one dowel or dowel bolt, but with soft alloy casings it is possible to misalign them, then use the bolts to clamp them up, so cutting a new oval hole in the casing. The resultant misalignment of the clutch will result in judder, sudden engagement, and ultimately the centreplate tearing apart.
Of course none of the above are caused by a cheap clutch.
The gearbox input shaft splines should not be greased, at all. If when clean, the centreplate does not move smoothly on the splines, rub them gently with the softest pencil you can find, then wipe off all excess graphite. Graphite is slippery, but will not attract dust or dirt. Grease will fly off once spinning, and contaminate the centreplate lining. I have seen grease on a lining causing judder, probably a quantity the size of a pinhead.
When you get it apart, you need to pay particular attention to the points I mentioned earlier. A new release arm is of little value if you don't make sure its bushes are good.
If you post very good quality pics of the clutch components, I may be able to help diagnose.