http://i277.photobucket.com/albums/kk59/studiofreak/bc44f6d63533f25a7489e0e46e923bb7.jpgThe lack of incline to assist with pressure of any kind (ok, i'm aware it's not a woodburning stove) is what i'd get sorted from the outset, the lack of angle to encourage throughflow is my personal bugbear with a tremendous potential to create an imbalance (speaking again only as a wb stove operator) where is the natural inclination for the exiting smoke to travel? ..even with a fan it needs draw, draw needs an exit, so my current perception is for a rocking inflow causing major turbulance without provision to exit in a prompt manner possibly a washing machine effect within, straight up & out, if you can bodge a temporary solution to run all that spare chimney flexible flue upright with minimal angle kinkage that would level the field somewhat as to poor air supply.
TBH being left to dry as you appear to have been i'd question the sale & product being "fit for purpose" & at the very least get that fan refunded here & now, provision for a fan sub £700 is easily do-able & in all likelihood a computer fan for a £5 would draw enough to make a difference once set up & working (ok i'm chancing my arm here & am not the consumate professional, however if a PC fan can assist a wbs or, as I use on my wood gasifying camp-stove ,very low tech to regulate burns to cook a meal, then i'd honestly question the integrity of salesfolks "add-ons" to this degree (if that's what it amounted to) that you've not had replies from in order to get the kit up & running.
it's a ruddy expensive bit of kit, it needs to work here & now! ..all the time it is down for a money making venture (despite the natural learning curve) I'd be incredibly aggrieved, as a former salesman If I left any of my customers in the lurch to this degree on a sale of £30 let alone several thousand I'd be hauled over the coals at head office without a doubt, get them on the phone (look at your sales contract, uk sale of goods act & EU sale of goods for good measure) & get them on the phone to uplift & refund the damn thing or get it sorted, their choice, adding in for good measure an agreed discount for your trouble incurred thus far, to do this you need to be sure in your own mind that you have done everything correctly, starting with that overly long chim-flex imho.( don't cut it, allow it to draw, upright, pole & wire support with a basic form of weather capping , but capping can come later.
(I don't wan't you getting antsy with them on the phone unless you are 100% clean.
New product requires a helping hand, no helping hand, give me a returns label & cart your stuff away as i'd have no faith in a company who neglects their paying customer, German folk i.m.e tend t have pretty good language skills, there is also google translate for basic translation, & ultimately a UK distributor should be the one with the skill to advise, sell & service your goods in a timely manner.