Freezer is building up frost and refrigerator is not cold enoough

Almost certainly, you have a leak within the freezer compartment.

The cooling system will use a divertor valve to concentrate coolant to the fridge or freezer compartment - whichever is necessary to maintain selected temperatures.

If a seal within either compartment is compromised and leaks then the coolant will be excessively diverted to that area in an attempt to lower it's temperature - the other section will suffer since more coolant is diverted to the weaker area; the weaker area that is being excessively cooled will also have more moist air circulating, hence moisture will contribute to a build up of ice - exacerbating the problem.

Ensure that both fridge and freezer doors are closing properly, if they appear to be secure then also check that the seals are airtight - there should be no ice accumulating around them.

You might need to re-align the doors, or less likely, replace the door seals.

Please reply if you require further clarification or help.