Re-engineer existing Wordpress website that has faults and make mobile freindly too

We are loking for somebody that can genuinely help us to re-engineer our existing Wordpress site. We are letting agents. The website has a CRM side to it allowing for properties to be uploaded via a third party CRM software on a daily basis. At the same time we are aware that we currently miss out on a good number of online visitors who are frutrated by our site not being 'mobile freindly' and want to resolve this too as soon as possible.