The Investigatory Powers Tribunal (IPT), established by RIPA, has exclusive jurisdiction to hear complaints about the intelligence agencies or interception (ss.65-70). However, since individuals are not automatically notified they have been the subject of interception or other surveillance, they have limited opportunity to contest it at the Tribunal.
The IPT is not one of the “senior courts” that under the Human Rights Act may make a declaration of incompatibility of UK law with the ECHR. It has no duty to publish any details of its negative decisions. Nor may decisions be appealed.
Before the Snowden revelations, there were only a handful of cases for which detailed decisions in this area had been published. More recently there have been a series of decisions, most significantly Liberty and others. The latter case marked the first time that the Tribunal had ruled against the security services.
The Anderson Review recommended that the IPT “should have an expanded jurisdiction and the capacity to make declarations of incompatibility; and its rulings should be subject to appeal on points of law.” 
 David Anderson Q.C., ‘A question of trust’, Report of the Investigatory Powers Review, July 2015, p.8.