SEO for website

I am looking for an SEO specialist/company to take over complete SEO for my website to get me to Page 1 Google (UK) for a number of key phrases. The web domain is about 2 years old but I have recently changed from an OS commerce site to Magento and sales have dropped. I have had SEO done before but with disappointing results and am looking for someone who can deliver what they promise. Ideally I would pay a monthly fee which would be reduced once rankings have been achieved for maintenance. I am looking for someone with great communication skills (excellent English a must) who can provide expected time frames for Page 1, who is easily contactable and will provide monthly reports etc. Please message me for more details.