WordPress expert on call

Hello - we have a great web site which has been professionally designed. We are regularly looking to update it and tinker with its design and, as amateurs, this often leads to the site losing it formatting and functionality. We need a reliable and responsive WordPress expert to be on call to make major and minor changes to the site, monitor its e-comm functionality for us and generally be there on the end of the phone when things need to get done fast. We will pay you an hourly rate to be agreed based on the actual amount of work we give you each month.Please demonstrate a long track-record of working with WordPress and show some examples of your best sites.