iphone 5 with bad data connection?

Hi,

I have an iPhone 5 and for some time I have a very bad data connection. Went through all the troubleshooting steps but no improvement. We have several other iphones in the house and the all work fine with good 3G and 4G. Tried interchanging SIM cards and that doesn't make a difference either. Looks like it's the Iphone 5. Have latest iOS installed. Any advice?