How can we rank our website on top of Google ?
You can’t.
If, you are in a mature and competitive market, (you are).
If, you want to target nationally, (you do).
If, you don’t have a unique offering, (you don’t).
If, your competition are long-established brands, (they are).
If, there are lots of them, (there are).
You don’t stand a chance - not unless you opt for very, very long-tail keywords that might bring you
the odd visitor.
At best and if you are lucky, an agency will spend months trousering your dosh then get your website to page 15 in the SERPS – after the shopping campaigns, the sponsored results, the instant answers, the local results and your competitor's organic listings. Whoopee.
Do what @fisicx says and get your website licked into shape. Then do what @Shopclicks says and spend your money on paid advertising.