I am reviewing my options at the moment, and have to say it is incredibly difficult to get any sense of a straight comparison here. So a bit of internet leg-work is required I'm afraid.
Internet deals seem to be much lower than anything available in shops, with all of the main suppliers. I am with Orange and have been for 6 years. Initially just landline and internet. When I moved here full time 2 years ago I upgraded to include mobile, opting to pay for the English speaking service. What a waste of time and money that was! Not one single change I have made to my account through the ES service has gone to plan. Not one. Forget about needing to speak English and start translating on the web, you get a much better idea very quickly of whats out there. You can then sound this out in a shop if you are unsure.
You can keep your mobile and landline number, allow 10 days for the service set up, make sure you are out of contract period and penalty free. Top advice seems to be get your new service installed before terminating your existing to make sure there isn't a period without any service. My current package with Orange is not what I signed up for at all, and is annoyingly cheaper if I went for a separate home and mobile contract. I am looking to change in the next month or so, and it seems that having a separate landline and mobile deal will be the cheapest. Even with Sosh a Subsidiary of Orange I can save 20/25€ per month.
Standard price for landline/internet with free calls to 80/100 countries plus mobile in France and sometimes DOR is 20€. All of the online pages have a line check system to make sure they can provide to you. If you have line issues now though that may need to be resolved first before another operator will be able to provide.
Good luck, and take that leap away from relying on English speaking services.