I feel sorry for those that have had a poor quality chair delivered to them, hopefully you can resolve any issues with OcUK directly. I kind of feel bad that mine has no damage or marks what so ever, given how disappointing this must feel to some who've already waited over a month for these, only to receive them less than perfect. Maybe it would be better to some degree if these were put together before leaving the warehouse and repackaged by OcUK?
The instructions are not great, while I have seen worse instructions before these could do with much improvement, they also are possibly for an earlier or later model as seen in step 7 both handles are actually on the same side rather than opposite sides.
Building was pretty straight forward, my advice would be to do steps 1 - 5, leave out step 6 for the moment (step 7 is already done for you), then put the base to one side, step 8 was virtually impossible to do as instructed, the bolts could do with being a little longer to make it far easier. The only way I could manage step 8 was to first unscrew the left side chair bracket off the bottom, this did make the sides a little easier but it was still a struggle and a few swear words!, then reattaching the left side bracket to the bottom section of the seat.
Steps 9, 10, 11, 12 & 13 are already done for you. Do 14, 15 and 16 in that precise order, be very careful with the placing of the plastic covers in 14 & 16 make 100% sure the two recesses inside are covering the bolt heads properly before screwing them down, don't over tighten them either.
Follow steps 17 & 18, step 19 is made easier by attaching the mechanism to the chair before the base as in step 6.
Disclaimer: Don't blame me if you follow my installation advice and still manage to F it up
@awesomeclaw, the bottom straps of the lumbar support don't need to go around the sides like you have it in your picture, they should go between the bottom and the back on the inside of the chair, its a tight squeeze but you can press down the foam enough to slide them through. The support pillow can also just be placed over the top of the headrest, rather than through the straps, not saying your way is wrong though BTW.