Start by looking at the attributes that build trust in the first place. The top 5 are:
4. Excellent service
5. Great staff
Any significant action that a company plans to take should be assessed against the impact that it would potentially have on any or all five of the above and attributes. If the action would result in a negative reaction simply don’t do it because that would damage trust. If you still decide to go ahead with a particular action HOW you plan to carry it out should then be assessed against the top 5 list.
The model for the most trustworthy retailer is always John Lewis and their supermarket chain Waitrose. Interestingly Waitrose are rarely the cheapest and in spite of the John Lewis promise to never be knowingly undersold some of their own products are quite expensive. But, since everyone trusts them on all 5 points price becomes much less relevant.