I don't understand how this criticism applies to OPs service. Why do you think the emissions aren't really truly being offset?
It looks like they provide 5 different CO2 capture services through different partners, and the projects methods and details are widely available. You can choose any desired ratio of the 5. Of these 5, 4 of them seem to be methods that, for a cost, directly and physically remove a known quantity of CO2 from the atmosphere. Only one, Forestation, seems to be potentially prone to the type of ambiguities you mention, where the intended impact never actually occurs, but this depends on if it's actually being done properly. The partner they are using is onetreeplanted, which seems to be endorsed by or partnered with a lot of credible environmental organizations.
Minor correction in that our primary forestation partner is Eden Forestation (although we have used OneTreePlanted in the past) but everything else you mention is accurate - thanks!
It looks like they provide 5 different CO2 capture services through different partners, and the projects methods and details are widely available. You can choose any desired ratio of the 5. Of these 5, 4 of them seem to be methods that, for a cost, directly and physically remove a known quantity of CO2 from the atmosphere. Only one, Forestation, seems to be potentially prone to the type of ambiguities you mention, where the intended impact never actually occurs, but this depends on if it's actually being done properly. The partner they are using is onetreeplanted, which seems to be endorsed by or partnered with a lot of credible environmental organizations.