I found that these logos from these so called logo sites are not always accurate (most the time they are not), or they 1000 vector points when only need 12, so I try not to use them.
Contact the company directly and if your client is a legit company (reseller) they will normally provide the logos or images to you by access to official dealer sites. I do this all the time and never have a problem getting quality vectored images (sometimes only provide Jpegs) I always make sure my client know I will be contacting them first though.
If that does not work or too hard to get ahold of someone you can usually find find better quality logos going directly to the company's website and pulling a quality vectored logo off of a PDF from the website. Look for manuals or sales brochures.