You're doing them a favor? Ok. How about at least admitting that it's at least (hopefully) a win-win for both sides.
I don't think calling is a breach of their contract. Did they explicitly say in the contract that they will NOT call you? Also - if you don't want any more calls from them - all you need to say to opt out is "I do not wished to be called again. Please take me off your call list." And then if they call again, you can try and take action. It's not an easy thing to "win" - but you can at least try and have legal footing.
As I said - I can understand why you don't want or like to be called. But I can't really believe you're surprised.
Also - let me ask you this - because I honestly don't know how they are working this deal. Is it your phone number they are calling you on, or one they provided for the test. Honestly curious. Because if it's the latter - then they really do have a right since it's technically their number.
They are calling the number that I provided them. So my number. If they called the phone they provided I wouldn't be as upset.
I believe it is a breach of contract because it specifically states in the agreement that they have the right to email you promotions and about the test drive. But nothing states they have the right to give your number to a local Samsung rep to try and sell you a device.
I can't tell them not to call me because I currently have their device. If they keep calling me after I return it, then I will pursue action.