Water Softener Salt Change

Need some advice:  We have a 2-yr old Culligan water softener in our rented house and need to have the salt changed.  We have tried contacting Culligan via their website in English and French.  (Unfortunately we cannot call because we are not fluent enough in French).  We have not received any responses.

Then we started contacting other water softener companies.  None of them will change salt for another brand.  They will change out the whole system for $1500....but they admit that is silly for a new system, and we should contact  Culligan.

What am I missing here?  Isn't there any company that can change salt for us on a ‘generic' basis?

You can change it yourself without problem. Just go to Hubo shop and buy a generic salt.

I agree.  The salt is not specific to particular makes of softener. 
You shouldn't use salt that is for clearing snow off paths, but any salt that is for water softeners is OK.
You don't need to change it though - just top it up, or more precisely don't let it get completely empty.  What makes you think you need to have the salt changed?