This company is not Asus, their bad work should not discredit Asus. I don't think that claiming to be Asus Technical Certified actually means much - I mean, do they actually have some sort of official Asus Technical Certificate hanging on the wall? - I think they're just listing all the big laptop brands on their business card to inspire customer confidence, lol.
Can you take your laptop back to them and point out the faults in their work? They might offer to correct any incidental problems caused by their earlier work, it has only been a day or two. A reputable company would make the effort to ensure customer satisfaction (and return business). If they are indeed Asus Certified then I'm sure they have to meet certain standards when servicing Asus products, failure to do so could justify an Asus-approved (and Asus-paid-for) RMA process. I'd approach them first, personally, no need to involve Asus if there's no problem for Asus to fix.