The retailer wont serve my address
Retail energy plans are priced and are published by distribution zone - each zone is run by a single regulated monopoly energy distributor which looks after the poles and wire and physical infrastructure that delivers energy to your home. Distributors set pricing for network access, which gets rolled up into the pricing for retail plans in that zone.
All this is a long way of saying that retail plans and prices are published per zone, in order to accommodate the differing network charges that apply in different zones.
However, individual retailers are free to set their own internal rules on postcodes and locations they choose not to serve, even when that location falls into a zone that they more generally do serve, and have published prices for.
They are not obliged to publish any information on the individual locations they choose not to offer their products for, so Bill Hero cannot reliably exclude these plans.
Bill Hero relies on the per-zone plans that retailers publish, and so its possible that Bill Hero may display a plan in a results set, because its generally available across your distribution zone, but the retailer might refuse to offer that plan for your specific location.
If this situation occurs for you, please move to the next-ranked plan in your ranked results.