Customers fail to re-evaluate short-duration tariffs

[jecollins]

Customers can currently be exploited by a broker who issues a tariff with a high rate, a big signup bonus, and a short expiration interval. Customers will trade off the signup bonus against the rate over the expiration interval and decide to subscribe. However, the high inertia prevents them from following through and dropping the subscription after the expiration interval. Perhaps subscribing to such a tariff should invoke a re-evaluation after the expiration.

[jecollins]

To clarify: the "expiration interval" is represented by minDuration in the tariff spec, and matters only in the case when there is a penalty for early withdrawal. If there's no penalty, then a customer who received a signup bonus should re-evaluate at the next opportunity, in order to not be stuck with unattractive terms.

[jecollins]

The obvious fix is to ignore the signup cost/bonus for the current tariff in tariff evaluation. This should have always been the case.

[jecollins]

Actually, the code already ignores signup bonus/cost for the current tariff. What it does not do is reduce the inertia in the case where the current tariff was (possibly) the best deal just because of its signup bonus. A customer who is suspicious of a signup bonus would presumably be paying attention once it had received the bonus.

[jecollins]

The fix is to reduce inertia to zero if the current tariff has a positive signup payment. Possibly it should be reduced to a small non-zero value.

[jecollins]

Ideally the reduced inertia value would be a parameter, perhaps defaulted to zero.

[jecollins]

Fixed. Default parameter value could be non-zero, still needs some discussion.