I'm not prejudice but never, EVER take advice from Indian SEO companies... they don't know anything (for the most part).
Individual keyword density of 5-6% will get your site banned from Google. Anything over 3% is called Spam by Google.
Having said that, ALL the keywords you are targeting together should account for 5-10% of your content (depending on what they keywords are / how specific they are / how many you are using).
Sorry, but IMO if you are marketing web design and don't know how to utilize keywords properly then you won't be getting many sales anyways. Either way, don't get me wrong, I wish you the best!